The present disclosure relates to a lock-up clutch control device and control method capable of coupling and decoupling a motor of a vehicle and an input shaft of a transmission to and from each other.
Hitherto, there has been known a control device that performs slip control in which the actual slip speed (actual rotational speed difference) between a motor and an input shaft of a transmission is caused to coincide with a target slip speed, including: a first feedback compensator (proportional-differential (PD) controller) that has a frequency characteristic in which the gain of low-frequency area of deviation between target slip rotation and actual slip rotation is set smaller than the gain of high-frequency area and that inputs the deviation and outputs a first slip rotation command value; and a second feedback compensator (proportional-integral-differential (PID) controller) that has a frequency characteristic in which the gain of low-frequency area of the deviation is set larger than the gain of high-frequency area and that inputs the deviation and outputs a second slip rotation command value (see Japanese Patent Application Publication No. 2010-270822, for example).
In order to improve the transient response characteristics of slip control during starting of the vehicle, the control device switches from feedback control by the first feedback compensator to feedback control by the second feedback compensator in accordance with the magnitude of a delay in response of a clutch hydraulic pressure, that is, the control amount for deciding the torque capacity of a lock-up clutch, during starting of the vehicle. Then, in switching between the feedback compensators, the assignment of weights to the first slip rotation command value and the second slip rotation command value with respect to a slip rotation command value is gradually varied. As the control amount for deciding the torque capacity of the lock-up clutch, the pressure difference between an application pressure and a release pressure that act on the lock-up clutch, the torque capacity of the lock-up clutch estimated from the engine torque and the engine rotational speed, or the like is used. In addition, Japanese Patent Application Publication No. 2010-270822 also describes use of a map in which regions for switching between the feedback control by the first feedback compensator and the feedback control by the second feedback compensator using the engine torque and the engine rotational speed as arguments are prescribed in advance.